In industry, there is a constant need to lubricate moving systems, such as moving axles, rotating bearings and other machine elements having surfaces that bear and glide on each other. In some cases, lubrication-free components may be used: This is however only possible for lower loads and slow moving speeds. For other systems, where high loads are imposed on the bearing surfaces and/or where the speed, either rotational or linear, is relatively high, there exists a need to lubricate the surfaces. The periodicity of the application of lubricant and the amount of lubrication applied may vary extensively. In some cases, a small amount of lubricant may be required every day and in other cases, lubrication may be performed every three months.
Especially when the lubrication must be performed at short intervals, and also where the lubrication point is hard to reach, an automatic lubrication device is advantageous. There are known lubrication devices that comprise a pump of some kind, a lubricant reservoir such as a grease container and a control unit that dispenses a predefined amount of lubricant to the lubrication point at predetermined time intervals. Such a system is rather complicated and the size is often rather large.
Another type of automatic lubrication device is a self-contained grease container which somewhat resembles a grease cartridge. Such a grease container comprises a gas generating cell and a compartment of grease which dispenses grease from the compartment to the lubrication point. The gas generation may be based on a dry cell that produces gas in an electrochemical way. The amount of generated gas is controlled by the current flowing from a gas generating electrode to a counter electrode. The generated gas will build up a pressure inside the container which in turn causes a piston to dispense grease from a lubricant opening.
Such a lubrication device is known from U.S. Pat. No. 5,012,897. In this lubrication device, two gas cells are connected to each other through a fixed resistor by an intermediate spring. By screwing the top part of the device into the container lid, the spring connects the two cells such that the electric circuit closes and gas starts to generate. The top part may be unscrewed somewhat in order to disconnect the electrical circuit, and by unscrewing the top part completely, new gas cells may be fitted.
One disadvantage of being able to replace the gas cell in an easy way is that the manufacturer of the lubrication device cannot guarantee a proper function of the lubrication device since it is possible to tamper with the gas cell. By replacing the gas cell, there is a possibility for the user to insert a used gas cell with a reduced capacity, which would lead to a reduced life of the lubrication device compared with what was expected. It is also possible to insert a different type of gas cell or to position the gas cell in a wrong way, which would also lead to a malfunction of the lubrication device. In those cases, the lubrication of the machine part may fail with a breakdown as result. Further, it is possible to damage parts of the gas generating device which will also lead to the lubrication device not functioning properly.
DE 102004 013594 describes a lubrication device in which the lid may be used to set the amount of dispensed lubricant. The lid of the container is provided with a rotatable part comprising a potentiometer element. The rotatable part is provided with protrusions that stop the rotatable part from being removed once it is in position. The lid is fixedly attached to the container. In this way, the container may not be refilled and the gas cell may not be removed or replaced.
In this lubrication device, the user has no possibility to tamper with the gas cell. There is however no possibility to dispose of the gas cell in a proper manner. The gas cell, and in this case also the battery cell, should be removed before the rest of the lubrication device is disposed of. This makes it difficult to recycle the parts of the lubrication device. There is thus room for improvements.